Into the 'Mouth of Hell'

A journey into the crater of an active volcano

Ken Sims peers over the rim of Masaya Volcano and looks 2,000 feet (600 meters) down into the smoking crater lined with rows of jagged rocks that jut up like monstrous teeth. A 16th-century Spanish friar once called it “the mouth of hell.”

Sweat drips from Sims’ forehead on this sweltering Nicaraguan morning. The temperature is already 100°F (37°C). Only the vultures move quickly, spreading their black, bony wings to ride hot winds across the crater.

With the wind comes the gas, which Sims and several colleagues are here to study. Sulfur-laced gusts swirl into Sims' face as he organizes his climbing ropes. He coughs and pulls up his gas mask. The air reeks of rotten eggs, a signature scent of a smoking volcano.

Sims is not worried that Masaya will erupt, as it last did on April 23, 2001. That unexpected spasm expelled a small amount of ash and rock that burned a woman’s arm, started a fire, and damaged several nearby cars and tour buses. Now seismometers monitor the volcano’s every twitch and provide warning.

Still, it’s one thing to look down the throat of a volcano. It’s another to climb inside.

Hundreds of years ago, those who ventured into Masaya did so against their will. Ancient Nicaraguans believed the volcano was inhabited by a lava-spitting demon; they tried to appease it by throwing in young women and children.

But for Sims, the volcano is a laboratory. For 30 years, Sims and his friends John Catto and Dennis Jackson have climbed mountains, frozen waterfalls, and rock walls around the world for sport. In March 2006, with permission from Nicaraguan national park officials, they descended into the volcano for research.

Earth's 'plumbing system'

Experts in volcanic gases ordinarily work on the rims of volcanoes. But Sims, a Colorado native, reached the top of his first 14,000-foot (4,267-meter) mountain at age 8 with his father. He possesses both the climbing skill and scientific knowledge to safely collect gas samples directly from the caldera, where it is most concentrated.

By gathering gas samples from volcanoes worldwide, Sims is exploring how our planet is evolving and how volcanic gases cause climate changes that may have led to the extinction of dinosaurs. Studying the gases also helps scientists understand when the volcano might erupt and what effect gas emissions may have on human health.

Since joining the Geology and Geophysics Department at Woods Hole Oceanographic Institution (WHOI) in 1997, Sims has collected gas from Mount Erebus in Antarctica and Mount Etna in Italy. This fall, he will travel to Nyiragongo Volcano in the Congo and to Kilauea Volcano in Hawaii. Sims is continuing to collect a library of global volcanic exhaust to learn about what he calls “Earth’s plumbing system.”

The volcanoes he ventures into meet two criteria. They regularly serve up plenty of gas for sampling. They are monitored for telltale movements that might indicate an impending eruption. This makes them safer to study.

“I want degassing volcanoes,” Sims said. “Not exploding volcanoes.”

Masaya the mushroom

Every volcano has its own hazards and geology.

Masaya, for example, doesn’t measure up to the traditional image of a volcano as a tall, conical mountain with lava spouting from its tip. Only 2,083 feet (635 meters) high, Masaya is a small fry compared to a dozen other volcanoes towering twice as high over the Nicaraguan countryside.

Nicaragua’s tallest volcanoes—Concepción, Mombacho, and San Cristóbal—are featured on postcards sold in local markets. Masaya, however, squats on the landscape like a lumpy mushroom.

What Masaya lacks in grandeur, it makes up for in gas. Located in Masaya National Park in southwestern Nicaragua, the volcano is a Central American tourist stop for those who come to gaze at its smoky white plumes.

Each day, 6,000 metric tons (13,230,000 pounds) of gas waft from a conduit 60 feet (20 meters) in diameter in the center of Masaya’s inner crater. For 70 Nicaraguan córdobas (about $5), anyone can drive the 6.6-mile (10-kilometer) paved road to the volcano’s rim for a nose-wrinkling whiff of exhaust from the Earth’s interior.

The expedition team

Unlike other volcanoes, Masaya vents gas that has not been filtered through or chemically altered by groundwater. Instead, the gas escapes directly from underlying magma, through the conduit, and into the open air.

This access to pure volcanic gas first drew Sims and three European colleagues to Masaya in 2003 and brought them together again in March. Each of the scientists studies a slightly different aspect of the gas. After their individual analyses, they will piece the research together to form a clearer picture of the volcano as a whole.

French geochemist Pierre Gauthier at the Laboratoire Magmas et Volcans, operated by the Centre National de la Recherche Scientifique at the University of Clermont-Ferrand, works from the rim. Gauthier, a specialist in volcanic gases, collects gas in a homemade device crafted from a noisy handheld vacuum cleaner secured with silver tape and powered by a motorcycle battery.

“In France, money for volcanology is tight these days,” Gauthier said. “So we have to have a lot of ingenuity.”

British volcanologists Tamsin Mather and David Pyle of the University of Cambridge, along with their postdoctoral investigator Melanie Witt, are interested in a variety of metals emitted in the volcanic gas. Among them is mercury, which is known to be toxic to humans.

"We are trying to understand volcanoes as a mercury source,” Mather said. “How much comes out of volcanoes? How does it move around the Earth? What role does it play in the environment? If we can understand this at a couple of volcanoes, we can start thinking about it on a global scale and how such emissions are distributed.”

Rounding out the expedition team are Sims’ two climbing friends, who helped ensure safe passage into the volcano.

‘A pretty strange place’

The biggest hazard the men encounter in Masaya isn’t an eruption, choking gas, heat stroke, or collapsing crater walls. It is the possibility of knocking loose rocks onto each other as they climb. They avoid this on the way into Masaya by descending one by one and waiting behind huge boulders while the others climb. It takes two hours to reach the crater floor, but these men know that safe climbing requires patience.

John Catto, 45, is a Rocky Mountain-based adventure photographer and video producer who met Sims in the early 1980s while studying geology at Colorado College. In addition to making several first ascents on mountains worldwide, Catto has documented climbs as a cameraman and producer for National Geographic and The Discovery Channel, among others.

Dennis Jackson, 64, is a professional guide who has taught climbing to youth and adults and has authored two books on climbing. He has been climbing and guiding with Sims for three decades.

Catto ventured into Masaya with Sims in 2003, but this is Jackson’s first glimpse of the volcano. Standing at the southeast side of the crater, his gaze drifted from the droopy rim down the first 400-foot (121-meter) slope coated with boulders and dehydrated volcanic crumbs. He noted the 200-foot (60-meter) vertical wall they will rappel. His eyes finally stop at the sloping, rock-strewn crater floor surrounding the smoking crater, where they will set up Sims’ instruments.

“That looks pretty gnarly,” Jackson said before turning to read a sign posted for tourists. “En caso de explusión de rocas puede protegerse debajo del vehículo,” it says in Spanish, next to the English translation. “In case of expulsions of rocks, you can protect yourself under the car.”

“This guy has dragged me to some pretty strange places,” Jackson said, nodding at Sims. “This may be one of the strangest.”

Where does gas come from?

Volcanic gases are created in hot, melting rock called magma, which resides deep in the pressure cooker that is Earth’s mantle. It is driven upward by buoyancy and pressure. As the magma draws near the planet’s surface, the pressure is relieved. Gases are released and start to bubble, as soda often does when you open a bottle.

Ultimately these gases break through weak areas in the planet’s crust and slowly leak out of fumaroles, geysers, and hot springs. More explosive eruptions, such as Mount St. Helens, Vesuvius, and Krakatoa, have made history.

When gas escapes, it immediately begins to change, coalescing around tiny particles in the air and forming a visible haze. On sunny days, Masaya resembles a huge, smoldering bonfire as gas plumes slowly drift up from the crater, flow over the rim, and spread out.

Sims’ goal is to catch the gas while it is still concentrated—long before it disperses across the landscape and into the atmosphere. He does this by getting right up to the smoking conduit and sucking gas into portable instruments.

One instrument gives him an immediate readout of gas compositions and concentrations. Another instrument gathers tiny amounts of rare metals ferried out of the mantle by the gas. They collect on thin, round paper filters that he brings back to WHOI for analysis.

Radon 'clocks'

Sims can’t pick up volcanoes and see what’s happening underneath, or travel back in time to see how the planet was created. But the volcanic gases and lavas provide him with clues to unravel the magmatic processes that have shaped Earth’s surface, atmosphere, oceans, and climate over billions of years.

Plentiful varieties of gases emanate from Masaya, including carbon dioxide, water vapor, sulfur dioxide, and hydrogen sulfide, but Sims focuses on one that flows out in very tiny amounts: radon.

Radon is a colorless, odorless gas that can be dangerous when vented naturally from the ground and trapped in homes. When inhaled, its radioactivity can lead to increased risk of cancer. Masaya pumps out a small but steady supply of radon in quantities that aren’t harmful to people.

Radon comes from uranium, a naturally occurring, radioactive element throughout Earth's crust and mantle. During its long, slow cascade of nuclear decay, uranium transforms into other elements, including radium, which produces its namesake gas.

“We can use the radon as a clock,” Sims said. Radon decays into various isotopes with known half-lives. One isotope, radon 222, for example, decays very quickly into polonium 218 after it is released from a magma chamber—it has a half-life of 3.82 days. By analyzing radon isotopes, Sims can discern the timing of magmatic processes and draw conclusions about how fast the magma migrates from the mantle to the surface.

“If you don’t know the time scales over which magma is generated and migrates to the surface, your understanding of the system is extremely limited,” he said.

In the short term, knowing how quickly volcanoes expel gas can help reveal if new magma is coming into the magma chamber—a precursor for predicting imminent eruptions.

The demise of the dinosaurs

Getting inside volcanoes also allows Sims to capture gases with minute quantities of metals called platinum group elements, or PGEs.

Members of this group, among the rarest metals on Earth, include platinum, palladium, osmium, iridium, ruthenium, and rhodium. They concentrate heavily within Earth’s core, said Bernhard Peucker-Ehrenbrink, a geochemist at WHOI.

Scientists estimate that more than 99 percent of the PGEs on Earth are in the core. The remainder is mostly housed in the mantle. These metals make their way to the surface in magma and gas.

A small amount of PGEs, however, arrive on Earth’s surface via meteorites that crash into the planet. PGEs from volcanoes and from meteorites have distinct chemical signatures.

“Each has its own fingerprint,” Peucker-Ehrenbrink said. “When we sample PGEs, we are able to differentiate its source by looking at the different ratio of elements within the platinum group.”

This geochemical tool will help resolve a longstanding debate over what caused mass extinctions throughout history, such as the demise of dinosaurs. Some scientists say large-scale volcanic eruptions on Earth roughly 65 million years ago released huge volumes of particulates and heat-trapping gases that dramatically changed global climate. Other scientists cite evidence that a massive meteorite hit the Earth 65 million years ago.

“We also may find that it was combination of a major volcanic eruption and a giant meteorite impacting the planet,” Peucker-Ehrenbrink said. “An eruption could have caused the environment to deteriorate, and a big impact hundreds of thousands of years later may have been the final blow.”

Care to avoid contaminants

Studies that exploit the forensic potential of PGEs are now possible because of technological advances that give scientists the ability to measure PGEs more precisely and efficiently, Sims said.

Still, Peucker-Ehrenbrink calls the work at Masaya “among the most difficult we have done.”

“First, we’re working with extremely small concentrations of PGEs,” he said. Often they are looking for femtograms, or 10-15 grams, of PGEs in a cubic meter of air. That leads to the second difficulty: The scientists must assiduously prevent the introduction of even the tiniest amounts of contaminants that would corrupt any analyses.

A dust-strewn volcanic environment makes this tough. At Masaya, Sims takes great pains to make sure all his equipment—hoses, filters, gas-collecting instruments—are clean and protected by plastic wrap and plastic bags. While gathering samples in the crater, he carefully removes each thin paper filter and places it into labeled and sealed plastic dishes for transport to WHOI.

Peucker-Ehrenbrink and laboratory assistant Tracy Atwood then begin analysis by cutting each filter with ceramic scissors; metal scissors could introduce contaminants. They then heat each paper pile in a crucible at 1,832°F (1,000°C) with a small amount of nickel and sulfur.

After melting, the PGEs form a small bead at the bottom of the crucible, which is dissolved in acid to filter out the now highly concentrated particles. Finally, he places these filters in a mass spectrometer, which measures the concentration of each element within the samples.

The goal is to gather PGE information from gases at the different volcanoes and get an across-the-globe inventory of volcanic PGE emissions.

On the bottom of the crater

The crater floor of a volcano is an alien environment. Scorched brown and black rocks ranging from the size of peas to SUVs litter the ground where the crater’s walls have collapsed. There is little wind, no vegetation, and zero shade. The sloping floor crunches and slips under the climbers’ hiking boots.

“It’s like walking on ball bearings,” Catto said. The rocks are sharp, too. “If you slip,” he said, “you’re going to end up looking like pizza.”

From here, just meters from the crater, the exhaling gas sounds like the slow whoosh of a wave against a beach. It doesn’t take long to set up Sims’ instruments, which he powers using a motorcycle battery purchased in the town of Masaya.

For two days he collects radon; on the third, he collects metals. While the machines take in the gas, the men cautiously explore the crater. Once they find an orange rubber ball, perhaps tossed in by a tourist, which they bounce around until it is lost in the rubble. Mostly, they sit together and occasionally talk in muffled voices through their masks.

Hooked on mountains

Long before Sims discovered geology and chemistry, he began climbing mountains. He was 6 when he began hiking with his father near his Colorado Springs home. When he was in the third grade, they reached the top of Pike’s Peak. By 14, he took up technical rock climbing, using ropes and belays to scale vertical faces.

In junior high and high school, he took accelerated classes, which allowed him to spend his last six months of high school in Scotland. There he climbed 1,500-foot ice walls and began guiding others on climbing expeditions.

He returned to the United States in 1978 and spent the next 20 years teaching rock and ice climbing in New Hampshire at the Eastern Mountain Sports Climbing School and outdoor recreation skills in Colorado with Outward Bound. At the Santa Fe Mountain Center, he mentored adult and juvenile criminal offenders, teaching them outdoor skills during weeks-long backpacking trips.

He climbed frozen waterfalls and massive rocks throughout the western United States, Peru, and Europe with names like the Witch, the Shield, Cochina Spire, Argon Tower, Washington Column, and El Capitan. While building his climbing resume, he also returned to academics.

"After all the time I spent hanging around rocks, geology seemed like a logical course of study,” he said.

His studies at Colorado College, the University of New Mexico, the University of California, Berkeley, and at WHOI focused on how magma originated and moved within Earth’s mantle. It wasn’t until he was stuck in a 2002 snowstorm in Antarctica for a week with Gauthier that he began thinking about collecting his own samples of radon close to their source.

“It hadn’t been done before,” he said. “And I knew it was the missing link to understand volcanoes from bottom to top, from the mantle source to the erupting lava.”

Back on top

The trip out of Masaya’s maw takes two hours. Again, for safety, the men go one by one. Catto arrives first.

“Man, am I glad to be out of that hole,” he says. He drops his backpack with a thud and probes his mouth with a dusty index finger, relieved to find his teeth intact. Halfway up the climb, a rock fell over a vertical drop and hit the top of his red helmet, slamming his jaw shut and knocking him to his knees.

Jackson emerges next and immediately checks to see that Catto has not been injured. He then points to a spot in the canyon wall where green parrots, which fly into the volcano to roost at night, had dive-bombed him. The men share a tired laugh.

Sims arrives 10 minutes later as the sunset turns the sky orange and purple. He chugs a half-liter of water, then smiles and explains in his quiet voice that he’s pleased with his sampling. By the end of the trip, the men will make three treks inside Masaya and gather dozens of samples and radon recordings.

It will be a year or more before Sims, working with colleagues, can conduct their analyses and publish peer-reviewed papers on their findings. It’s likely that years will pass before he and other scientists can make conclusions about volcanoes and magmatic processes.

But one thing is for sure: They are tired and want to celebrate this small step toward a bigger understanding of the planet. They talk of hot showers, cold beers, and vegetarian burritos at a restaurant in town. Together they walk to the car. Jackson mentions that he's worn out.

“Science has been advanced today,” he said. “My body has not.”

Funding for Ken Sims' research comes from the National Science Foundation Divisions for Earth Sciences, Ocean Sciences, and Polar Programs. The Deep Ocean Exploration Institute at WHOI assisted with travel funding to Masaya. Sims gratefully acknowledges officials at Parque Nacional Volcán Masaya for their support.

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